Master/slave index in computer systems

Abstract

The master/slave index is an indexing method and apparatus that does not suffer from poor performance when stored in a file system by completely avoiding any seek operation when searching or updating the indexed information. Heterogenous attributes from objects of different types are split in a master index and at least one slave index, reserving no memory for non-existent attributes. Index tables can be merge-joined because they maintain their ordering across tables.

What is claimed is: 
     
         1 . An index system comprising: at least one master index table storing at least one attribute assigned to all objects; at least one slave index table storing at least one attribute not assigned to all objects, hence type-specific; a system to execute queries and update operations by joining table entries with a merge join or similar method 
     
     
         2 . The index system of  claim 1 , wherein the attributes to be indexed are derived from a file body (so-called “metadata”) 
     
     
         3 . The index system of  claim 2 , comprising at least one extractor to gather metadata 
     
     
         4 . The index system of  claim 3 , wherein the system is able to add or remove an extractor from the system 
     
     
         5 . The index system of  claim 3 , wherein at least one extractor is built into an application 
     
     
         6 . The index system of  claim 1 , wherein the attributes to be indexed are derived from tuples that are stored in databases 
     
     
         7 . The index system of  claim 6 , wherein the tuples are stored in a relational database 
     
     
         8 . The index system of  claim 1 , wherein the system is able to add or remove slave index tables 
     
     
         9 . The index system of  claim 1 , wherein data objects are added by appending tuples to the end of the master index and at least one slave index 
     
     
         10 . The index system of  claim 1 , wherein the index is searchable to identify data objects with certain properties, comprising the steps of: assigning a marker to each of the index tables, including but not limited to the master index and all slave indexes; determining the type of the data object from its attributes stored in the master index; reading the marked tuple from the appropriate slave index, if any is assigned to the specific type; advancing the markers in the master index and the assigned slave index to their next tuple; repeating this until all data objects have been processed 
     
     
         11 . The index system of  claim 1 , wherein data objects can be removed, comprising the steps of: assigning a marker to each of the index tables, including but not limited to the master index and all slave indexes; determining the type of the data object from its attributes stored in the master index; if the data object is referenced in the deletion list, removal of the marked tuples from the deletion list, the master index and the appropriate slave index, if any is assigned to the specific type; if the data object has not been referenced in the deletion list, advancing the markers in the master index and the assigned slave index to their next tuple; repeating this until all data objects have been processed or the deletion list becomes empty